Clean Water Act discharge permit · NPDES CT0100544
MYSTIC WPCF, Mystic, CT: NPDES CT0100544 discharge permit, effluent exceedances, inspections, penalties
- Administratively continuedPermit status
- MinorDischarger class
- 26Pollutants under a numeric limit
- 6Pollutants with an effluent exceedance
MYSTIC WPCF, held by STONINGTON-MYSTIC WPCF, holds NPDES permit CT0100544, which discharges to Mystic River. EPA’s file records it issued May 21, 2012 and expiring May 31, 2017. The status and dates are as EPA’s permit file stood when Velarion loaded it (October 14, 2026); EPA’s free Detailed Facility Report on ECHO carries the permit’s current standing.
Identity
| Facility as filed | MYSTIC WPCF |
|---|---|
| Permittee as filed | STONINGTON-MYSTIC WPCF |
| NPDES ID | CT0100544 |
| Permit status | Administratively continued (past its expiration date and still in force until reissued) |
| Permit type | Individual permit |
| Discharger class | Minor discharger |
| Facility type | Publicly owned treatment works |
| Program | Publicly owned treatment works |
| Issued | May 21, 2012 |
| Expiration date | May 31, 2017 |
| Issuing agency | CT DEP |
| Address | Mystic, CT 06355 |
| Receiving water | MYSTIC RIVER |
| Subwatershed | Long Island Sound Deep (HUC 020302030000) |
| Program components on file | Biosolids, POTW, Pretreatment |
| SIC | 4952 – Sewerage Systems |
Cited to the EPA ICIS-NPDES permit file (ECHO download) and EPA’s NAICS/SIC and component files, the same download.
Effluent limits and exceedances
- 32Pollutants on file
- 26Under a numeric limit
- 26With a violation of any kind
- 6With an effluent exceedance
An effluent exceedance is a discharge monitoring report value over the permit’s numeric limit (EPA’s violation code E90). A violation of any kind also counts a report not filed. Each row is EPA’s own count for that pollutant.
| Pollutant or measure | Limits | Violations, any kind | Effluent exceedances | Latest exceedance | Largest exceedance, as filed |
|---|---|---|---|---|---|
| Coliform, fecal general | 2 | 32 | 32 | July 31, 2022 | 99,999% over the limit |
| Enterococci | 2 | 29 | 29 | July 31, 2026 | 99,999% over the limit |
| Solids, suspended percent removal | 1 | 14 | 13 | August 31, 2011 | 260% over the limit |
| Solids, total suspended | 3 | 9 | 6 | July 31, 2009 | 290% over the limit |
| Chlorine, total residual | 2 | 5 | 3 | August 31, 2006 | 100% over the limit |
| Carbonaceous oxygen demand, % removal | 1 | 3 | 2 | April 30, 2010 | 173% over the limit |
| BOD, carbonaceous [5 day, 5 C] | 3 | 3 | 0 | ||
| Flow rate | 2 | 3 | 0 | ||
| pH | 2 | 2 | 0 | ||
| Oxygen, dissolved [DO] | 0 | 2 | 0 | ||
| Polychlorinated biphenyls [PCBs] | 1 | 1 | 0 | ||
| Solids, total, percent | 1 | 1 | 0 | ||
| Solids, fixed, % of total solids | 1 | 1 | 0 | ||
| Solids, volatile % of total solids | 1 | 1 | 0 | ||
| Zinc, sludge, total, dry weight [as Zn] | 1 | 1 | 0 | ||
| Lead, sludge, total, dry weight [as Pb] | 1 | 1 | 0 | ||
| Nickel, sludge, total, dry weight [as Ni] | 1 | 1 | 0 | ||
| Mercury, sludge, total, dry weight [as Hg] | 1 | 1 | 0 | ||
| Chromium, sludge, total, dry weight [as Cr] | 1 | 1 | 0 | ||
| Copper, sludge, total, dry weight [as Cu] | 1 | 1 | 0 | ||
| Cadmium, sludge, total, dry weight [as Cd] | 1 | 1 | 0 | ||
| Solids, settleable | 0 | 1 | 0 | ||
| Nitrogen, total [as N] | 0 | 1 | 0 | ||
| Flow, in conduit or thru treatment plant | 0 | 1 | 0 | ||
| Pass/Fail Static 48Hr Acute D. Pulex | 0 | 1 | 0 | ||
| Pass/Fail Static 96 Hr Acute Pimephales Promelas | 0 | 1 | 0 | ||
| NOAEL Static 48Hr Acute D. pulex | 2 | 0 | 0 | ||
| NOAEL Static 48Hr Acute Pimephales promelas | 2 | 0 | 0 | ||
| Phosphorus, total [as P] | 1 | 0 | 0 | ||
| Arsenic, sludge tot. dry wt [as As] | 1 | 0 | 0 | ||
| Beryllium, sludge, tot. dry wt [as Be] | 1 | 0 | 0 | ||
| Ultraviolet light dosage | 1 | 0 | 0 |
Cited to the EPA ICIS-NPDES limits and effluent violations files (ECHO download); up to 60 rows shown, most exceedances first.
Inspections, violations and enforcement
- 5Single-event violations
| Date | What EPA recorded | Agency |
|---|---|---|
| May 20, 2026 | Management Practice Violations - Improper Operation and Maintenance | ST6 |
| November 9, 2021 | WW SSO - Improper Operation and Maintenance | ST6 |
| August 27, 2021 | Management Practice Violations - Improper Operation and Maintenance | ST6 |
| August 27, 2021 | Reporting Violations - Failure to Notify | ST6 |
| August 9, 2018 | Management Practice Violations - Improper Operation and Maintenance | ST6 |
Velarion’s copy of EPA’s ICIS-NPDES files does not include the inspections, formal enforcement actions and informal enforcement actions files, so this page shows none of them. EPA’s free Detailed Facility Report on ECHO lists this permit’s inspections, enforcement actions and penalties.
Cited to the EPA ICIS-NPDES violation, inspection and enforcement files (ECHO download); up to 50 rows of each shown, newest first.
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EPA publishes a free Detailed Facility Report for every permit on ECHO: its compliance status quarter by quarter, its inspections, and its enforcement actions and penalties. EPA also sends free notices of new inspections and enforcement actions through ECHO Notify; enter NPDES ID CT0100544 there.
Nearby on the register
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- Every permit record in Connecticut, A to Z
Figures from EPA’s ICIS-NPDES download, loaded October 14, 2026.